Engine Automatic Control System And Method For Vehicles

Abstract

An engine automatic control system for a vehicle having an ignition switch for selectively connecting an electric source with an engine starter and an ignition circuit is provided which comprises an accelerator switch conducted in response to the operation of the accelerator pedal of the vehicle, a clutch switch conducted in response to the operation of clutch means of the vehicle, a starter conducting circuit for automatically operating the starter in response to the conduction of the mentioned two switches, a starter cutting-off circuit to stop the operation of the starter upon starting of engine rotation, a speed detecting circuit to detect the running speed of the vehicle and an engine holding/arresting circuit controlled by the speed detecting circuit to regulate in turn the operation of the engine of the vehicle.

Description

BACKGROUND OF THE INVENTION

The present invention relates to an automatic control system and method for an engine of vehicles, and more particularly to a novel automatic control system and method to stop engine operation when the vehicle is arrested and to drive the engine for starting the vehicle.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an engine automatic control system and method to prevent pollution of the atomospheric air caused by exhaust gas produced at idling rotation of the engine when the vehicle makes temporary stops at crossings, etc.

Another object of the present invention is to provide an engine automatic control system and method, having the above-mentioned characteristics, wherein the engine is automatically stopped when the vehicle is arrested and the engine is automatically driven for starting the vehicle, both operations being carried out without operating the ignition switch.

Yet another object of the present invention is to provide an engine automatic control system, having the above-mentioned characteristics, wherein the control system does not work to stop the engine operation when the vehicle is arrested on a slant place.

A further object of the present invention is to provide an engine automatic control system, having the above-mentioned characteristics, wherein the system does not work to stop the engine operation until cooling water for the engine gets to a predetermined or higher temperature.

Still another of the present invention is to provide an engine automatic control system and method, having the above-mentioned characteristics, wherein the engine is kept running at emergency or sudden stops when sudden starts of the vehicle is successively expected.

Yet a further object of the present invention is to provide an engine automatic control system, having the above-mentioned characteristics, wherein the combustion chamber of the engine can be kept cleaner and possible waste of fuel can be eliminated.

Still a further object of the present invention is to provide an engine automatic control system, having the above-mentioned characteristics, wherein the system can easily and simply be installed to any vehicle already in use.

The forgoing and other objects are attained in accordance with this invention through the provision of an engine automatic control system for a vehicle having an ignition switch for selectively connecting an electrical source to an engine starter and an ignition circuit which comprises an accelerator switch conducted in response to the operation of the accelerator pedal, a clutch switch conducted in response to the operation of clutch means, a starter conducting circuit for automatically operating the starter in response to the conduction of the mentioned two switches, a starter cutting-off circuit to stop the operation of the starter upon starting of engine rotation. Furthermore, the system is provided with a speed detecting circuit to detect the running speed of the vehicle and an engine holding/arresting circuit controlled by the speed detecting circuit to maintain the engine rotation while the vehicle runs and to stop the operation of the engine while the vehicle is arrested.

BRIEF DESCRIPTION OF THE DRAWINGS

The above mentioned and other objects and characteristics of the present invention will be more clearly disclosed in the following descriptions of preferred embodiments, especially when read in conjunction with the accompanying drawings, in which:

FIG. 1 is a block diagram of a system in accordance with an embodiment of the present invention;

FIG. 2 is a schematic circuit diagram of the embodiment in FIG. 1;

FIG. 3 is a schematic circuit diagram of another embodiment in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now referring more particularly to the drawings, in FIG. 1, there is shown a preferred embodiment of the present invention which comprises an ignition switch 1, an ignition circuit 3 connected to the IG terminal of the ignition switch 1 and an engine starter 4 connected to the ST terminal of the ignition switch 1. The mentioned three constructional portions are of well-known type and heretofore generally in use for motor-driven vehicles. And the system in accordance with the present invention further comprises a clutch switch 11, and an accelerator switch 12. A starter conducting circuit 5 is in communication with the IG terminal of the ignition switch 1 and the starter 4 and operates automatically the starter 4 in response to turning-on the clutch switch 11 and the accelerator switch 12. A starter cutting-off circuit 6 is connected to the starter conducting circuit 5, to the IG terminal of the ignition switch 1 through a manual changeover switch 2 and to the N terminal of an alternator 7 operated by rotation of the prime engine of the vehicle.

A speed senser 10 installed on a rotating portion of the vehicle power train incorporates with a speed detecting circuit 9 which controls an engine-rotation holding/arresting circuit 8. The circuit 8 is connected to the ignition circuit 3 to hold the circuit 3 conductive while the vehicle runs. On the other hand, the ignition circuit 3 is held non-conductive while the vehicle is arrested. A slope senser 13 is also provided with the system, which becomes off in accordance with the gradient of the roads. This slope senser 13 is connected to the engine-rotation holding/arresting circuit 8.

The circuits mentioned above will hereinafter be described specifically in details in reference with FIG. 2. The starter conducting circuits 5 comprises a transistor 52 to the collector end of which a starter relay 51 is connected. The clutch switch 11 and the accelerator switch 12 are in connection with the emitter end of the transistor 52 and are grounded. Resistors 20, 21 and 26 are connected with the base end of the transistor 52 and also in series with the IG terminal of the ignition switch 1 through the manual changeover switch 2.

The starter cutting-off circuit 6 comprises a voltage relay 61 regulated by the alternator 7. The voltage relay 61 is connected to the N terminal of the alternator 7. The resistance value of the resistor 21 is determined to be lower than that of the resistor 26.

The engine rotation holding/arresting circuit 8 comprises a transistor 80 and an ignition relay 81 directly connected to the minus terminal of the ignition coil within the ignition circuit 3. The ignition relay 81 cuts off current of the ignition circuit 3 when the transistor 80 becomes conductive. Connected to the base end of the transistor 80 are a diode 43 through a resistor 25 and a diode 42 in connection with the clutch switch 11 and the accelerator switch 12, the diode 43 being further in connection with the collector end of a transistor 92 within the speed detecting circuit 9. The slope senser 13 for detecting the gradient of the road is connected to the emitter end of the transistor 80 through a resistor 27.

The speed detecting circuit 9 comprises a transistor 90 conduction of which is controlled by opening and closing operation of the speed senser 10, and a condenser 36 to be charged through a resistor 57 while the transistor 90 is non-conductive and thereby to keep the transistor 90 constantly conductive. Conduction of the transistor 90 charges condensers 37 and 38 with minus potential. A transistor 91 becomes conductive by base voltage through a resistor 49 while the vehicle is arrested and then makes the transistor 92 non-conductive. Resistors 28, 29 and 30 are connected to the base end of the transistor 90. Resistors 53 and 56 are connected to the base end of the transistor 92 and grounded.

Provided further with the system are resistors 22 and 24 and Zener diode 41 to secure good operation of the system by discharging excessive voltage from the source. A condenser 33 holds a constant-voltage and the resistor 25 and condensers 32, 34 and 35 work to secure stable operation of the system.

The operation of the system of the present invention as described above is well explained hereinafter. While the vehicle is arrested with both of the manual change-over switch 2 and the ignition switch 1 turned on, that is, the B terminal is in connection with the IG terminal within the ignition switch 1, depression of the clutch and accelerator pedals closes and grounds the clutch switch 11 and the accelerator switch 12. The transistor 52 becomes conductive to operate the starter relay 51. Then, the starter 4 drives the engine of the vehicle. As the engine rotates, voltage is produced at the N terminal of the alternator 7 and the voltage relay 61 is put in operation thereof. Current supplied to the base end of the transistor 52 now flows to the voltage relay 61 to make the transistor 52 non-conductive. This prevents current supply to the starter conducting circuit 5 and the starter 4 is turned off. A condenser 31 works to stabilize the operation of the transistor 52 in switching-over.

In starting the vehicle, the accelerator pedal is gradually depressed and the clutch pedal is gradually released. At this moment, the transistor 80 kept non-conductive is about to become conductive when the clutch switch 11 becomes off or open by release of the clutch pedal. The transistor 80 is, however, kept to be non-conductive controlled by the speed detecting circuit 9 since the vehicle already runs at a certain speed. More specifically, while the vehicle speed is zero km/h, and the speed senser 10 is open, base current of the transistor 90 flows through the resistors 28 and 29 to keep the transistor 90 to be conductive. When the speed senser 10 closes by rotation thereof, the current is grounded through the resistor 28 and the speed senser 10 to make the transistor 90 non-conductive. At the same time, current flowing through the resistor 57 is charged to the condenser 36. Increase of the speed of the vehicle creates repeatedly on-off operation of the transistor 90 and charging of the condenser 36. On the other hand, the transistor 90 is kept constantly conductive by discharge of the condenser 36 and is amplified. And, in turn, the condensers 37 and 38 are charged with minus potential.

The transistor 91 constantly kept conductive by base current through the resistor 49 becomes non-conductive while base current thereof is used for direct-current conversion of minus charge of the condenser 37 to plus charge. Current supplied to the collector end of the transistor 91 through the resistor 54 now flows to the base end of the transistor 92 to make the transistor 92 conductive. And current so far grounded by the clutch switch 11 and the accelerator switch 12 through a resistor 23 and the diode 42 is supplied to the collector end of the transistor 92 through the diode 43 and is grounded.

When the vehicle runs on or over 2 km/h, base current of the transistor 91 becomes constantly necessary for direct-current conversion of the condenser 37. Thus, the transistor 91 is turned to be non-conductive and the transistor 92 is constantly held conductive. This conditions the transistor 80 of the engine-rotation holding/arresting circuit 8 to be non-conductive to keep the ignition relay 81 inoperative and the engine rotation is kept going.

When the vehicle is arrested on a flat ground, the accelerator pedal being released and the clutch and brake pedals being actuated, the slope senser 13 is kept closed and the transistor 91 within the speed detecting circuit 9 becomes conductive and the transistor 92 turns to be non-conductive. Base current flows to the base end of the transistor 80 of the engine-rotation holding/arresting circuit 8 to make the transistor 80 conductive. This operates the ignition relay 81 to cut off current supply to the ignition circuit 3. Consequently, the engine stops automatically after the vehicle is arrested.

In the case that the vehicle is arrested on a slant ground, on a slope, etc., the slope senser 13 becomes off or open and the emitter end of the transistor 80 is not grounded. Thus, the ignition relay 81 is kept inoperative. And the engine keeps running to prevent the vehicle from moving back on the slope when the vehicle starts running.

In emergent and sudden stops of the vehicle, the non-conductive and conductive periods of time respectively of the transistors 91 and 92 are prolonged by the period of time necessary for direct-current conversion of the condenser 38 after the direct-current conversion of the condenser 37 of the speed detecting circuit 9 is completed. Thus, the engine is kept rotating for the prolonged period of time as mentioned. This means that starting the vehicle soon after the sudden stop is possible since the engine does not stop and the rotation of the engine can smoothly be accelerated. In the system of the present invention, the timing for stopping the engine rotation after the vehicle is arrested can properly adjusted by determing capacities of the condensers 37 and 38 within the speed detecting circuit 9.

Referring to FIG. 3, another preferred embodiment of the present invention is described in detail as follows, wherein similar reference numerals are used to indicate similar parts. The differences between the first embodiment and this second embodiment are characterized in that in the second embodiment, the starter cutting-off circuit 6 is controlled directly by the engine rotation and a thermosenser 14 is additionally connected to the engine-rotation holding/arresting circuit 8. All the other constructions are just same as those of the first embodiment and no description is made covering the same constructions.

The starter cutting-off circuit 6 comprises a transistor 90' conduction of which is controlled by opening and closing operation of the point of the ignition circuit 3. Provided also with this circuit 6 are a condenser 36' which is charged through a resistor 57' when the transistor 90' becomes non-conductive. A condenser 37' is charged with minus potential when the transistor 90' becomes conductive. A transistor 92' is turned to be non-conductive while the engine stops by a transistor 91' which is turned to be conductive by base voltage supplied through a resistor 49'. Resistors 28', 29' and 30' and a diode 58 are connected to the base end of the transistor 90'. A diode 53' and a resistor 56' are connected to the base end of the transistor 92' and are grounded. The collector end of the transistor 92' is connected to the base end of the transistor 52 of the starter conducting circuit 5 through the resistor 26. A condenser 59 is for positive feedback of the transistor 90'. A diode 60 and a Zener diode 62 are to discharge excessive voltage to secure the operation of the transistor 90'. A condenser 70 is adopted for stabilizing switching-over operations.

The engine rotation holding/arresting circuit 8 comprises a thyristor 81' connected to the minus terminal of the ignition coil within the ignition circuit 3 through a resistor 82 and operated by conduction of the transistor 80. Thus, the ignition circuit 3 can be cut off. When the slope senser 13 becomes off or open or when both of the clutch and accelerator switches 11 and 12 becomes open, a transistor 83 is turned to be conductive and the transistor 80 becomes non-conductive. Turning-on of the thermo-senser 14 makes the transistor 80 non-conductive. Non-conduction of the transistor 80 keeps the ignition circuit 3 to be conductive. Connected to the base end of the transistor 80 are the diode 43 connected to the collector end of the transistor 92 of the speed detecting circuit 9 and the diode 42 connected to the clutch and accelerator switches 11 and 12. A resistor 88 and a condenser 89 are adopted to stabilize switching-over operation of the thyristor 81'.

In the above-mentioned embodiment, while the vehicle is arrested with both of the manual change-over switch 2 and the ignition switch 1 turned on, that is, the B terminal is in connection with the IG terminal within the ignition switch 1, depression of the clutch and accelerator pedals closes and grounds the clutch switch 11 and the accelerator switch 12. Current runs through resistors 20, 55' and 26 with smaller total resistance and becomes base current of the transistor 52. Thus, the transistor 52 becomes conductive to operate the starter relay 51, which, in turn, lets the starter 4 start the engine of the vehicle.

As the engine rotates, in the starter cutting-off circuit 6, current is grounded through the resistor 28' and a diode 58 while the point of the ignition coil is closed. At the same time, the condenser 36' is charged through the resistor 57'. While the point of the ignition coil is open, current flows through the resistors 28' and 29' in series connection to become base current of the transistor 90' which is turned to be conductive. In accordance with the engine rotation, on-off operation of the transistor 90' and charging of the condenser 36' are repeated. The transistor 90' is, however, constantly kept to be conductive by discharge of the condenser 36'. This increases potential difference between the collector and emitter ends of the transistor 90' and correspondingly to the potential difference increase, minus potential is charged within the condenser 37'. The transistor 91' conditioned to be constantly conductive by resistors 49' and 48' and the condenser 37' becomes non-conductive while base current thereof is used for directcurrent conversion of the minus charge of the condenser 37' to plus charge.

When the engine rotation increases up to 800 r.p.m. or more, the transistor 91' is constantly kept non-conductive and collector current of the transistor 91' turns into base current of the transistor 92' through a resistor 54' and a diode 53'. This turns the transistor 92' to be conductive. Base current so far supplied through a resistor 55 to the base end of the transistor 52 is cut off to make the transistor 52 non-conductive. Thus, the starter relay 51 becomes inoperative to arrest operation of the starter 4.

When the engine rotation is further increased and the vehicle runs faster, the transistor 80 of the engine rotation holding/arresting circuit 8 is kept non-conductive controlled by the speed detecting circuit 9 in the processes as previously described in the first embodiment. The thyristor 81' is held to be off to secure conduction of the ignition circuit 3 and the engine keeps rotating.

When the vehicle is arrested, controlling operation of the engine rotation holding/arresting circuit 8 regulated by the speed detecting circuit 9 makes, as in the first embodiment, the transistor 80 conductive to cause the thyristor 81' to be operative. This shuts off the ignition circuit 3 to arrest automatically the engine rotation. In case, however, the vehicle is arrested on a slant ground, the slope senser 13 becomes off and current is supplied to the base end of the transistor 83 through resistors 84 and 85 in series connection. Thus, base current of the transistor 80 being cut off, the current flows to the collector end of the transistor 83 through the resistor 23. This makes the transistor 83 conductive to keep the ignition circuit 3 conductive, which, in turn, holds the engine rotation.

In the case the temperature of engine cooling water stays lower than, for instance, 50.degree..+-.7.degree.c while the vehicle is arrested, the thermo-senser 14 becomes on to each current through the resistor 23 and a diode 95. Then, the transistor 80 becomes non-conductive, which holds, in turn, the thyristor 81' to be inoperative. And the ignition circuit 3 stays to be conductive and the engine keeps rotating. When the clutch and accelerator switches 11 and 12 are turned to be open while the speed of the vehicle is zero km/h after the engine is started, discharging of a resistor 93 and a condenser 94 keeps the transistor 83 conductive for a time being and the engine rotation is held.

Capacities of the condenser 36' and a resistor 50' within the starter cutting-off circuit 6 are changed in correspondence with numbers of the cylinders of the engine. For instance, in comparison between a four cylinder engine and a six cylinder engine, the capacity of the condenser 36' is larger with the four cylinder engine, meanwhile, the resistor 50' has a larger capacity with the six cylinder engine.

In the mentioned two preferred embodiments, the clutch and accelerator switches 11 and 12 are operated by the clutch and accelerator pedals respectively. The clutch switch 11 can, however, be adapted to a vehicle equipped with an automatic transmission system by way of proper means.

As well described above, the present invention enables to stop automatically the engine without cutting off the ignition switch when the vehicle is arrested and to start automatically the engine in starting the vehicle. Without causing any troublesome operation to the driver of the vehicle, the engine can be stopped when the vehicle is arrested at crossings and the like, thereby to prevent the engine from exhausting waste gas in idling rotation. The specific consumption of fuel is also much lowered.

Thus, it will be clear that variations of the details of construction which are illustrated and described may be resorted to without departing from the true spirit and scope of the invention as defined in the appended claims.

Claims

What is claimed is:

1. An engine automatic control system for a vehicle having an ignition switch for selectively connecting an electric source with an engine starter and an engine ignition circuit comprising, a first switch to be closed by depression of an accelerator pedal of the vehicle, a second switch to be closed by disengaging operation of clutch means of the vehicle, a starter conducting circuit for connecting said electric source with said starter in response to the closing operation of said first and second switches, a starter cutting-off circuit for detecting the start of engine rotation caused by said starter and cutting off current supply to said starter, a speed detecting circuit for detecting the speed of the vehicle, an engine rotation holding/arresting circuit controlled by said speed detecting circuit and for maintaining said engine ignition circuit conductive while the vehicle runs and for making said ignition circuit non-conductive when the vehicle is arrested, and delay means for inhibiting the non-conductive state of said ignition circuit upon start of said engine for a predetermined time to permit said vehicle to move.

2. The control system as set forth in claim 1, wherein said system comprises slope sensing means for detecting the gradient of places where the vehicle is arrested so that said means controls said engine rotation holding/arresting circuit to maintain said ignition circuit conductive when the vehicle is arrested on a slant place.

3. The control system as set forth in claim 1, wherein said system comprises thermo-sensing means for detecting the temperature of engine cooling water so that said means controls said engine rotation holding/arresting circuit to maintain said ignition circuit conductive when the vehicle is arrested with said cooling water under a predetermined temperature.

4. The control system as set forth in claim 1, wherein said starter conducting circuit comprises a relay interposed between said starter and an ignition terminal within said ignition switch and a transistor conducted in response to the closing operation of said first and second switches, said relay being controlled by said transistor to connect said electric source with said starter.

5. The control system as set forth in claim 4, wherein said starter cutting off circuit comprises a voltage relay controlled by voltage appearing on an N- terminal of an alternator of the vehicle, said transistor of said starter conducting circuit turning to be non-conductive by operation of said voltage relay when said voltage reaches a predetermined value thereby to cut off current supply to said starter.

6. The control system as set forth in claim 4, wherein said starter cutting-off circuit comprises a first transistor controlled by on-off operation of the points of said ignition circuit, a first condenser for maintaining said first transistor constantly conductive, a second condenser for charging minus potential therein in accordance with conduction of said first transistor, a second transistor controlled by said minus potential of said second condenser, and a third transistor controlled by conduction of said second transistor, and third transistor regulating said transistor of said starter conducting circuit thereby to cut off current supplied to said starter when the engine starts rotating.

7. The control system as set forth in claim 1, wherein said engine rotation holding/arresting circuit comprises a transistor controlled by said speed detecting circuit and an ignition relay directly connected to the minus terminal of said ignition circuit, said ignition relay being regulated by said transistor so as to by-pass and ground current supplied to said ignition circuit when the vehicle is arrested.

8. The control system as set forth in claim 1, wherein said engine rotation holding/arresting circuit comprises a transistor controlled by said speed detecting circuit and a thyrister directly connected to the minus terminal of said ignition circuit, said thyrister being regulated by said transistor so as to by-pass and ground current supplied to said ignition circuit when the vehicle is arrested.

9. The control system as set forth in claim 1, wherein said speed detecting circuit comprises a first transistor controlled by a speed senser installed on a rotating portion of the vehicle power train, a first condenser for maintaining said first transistor constantly conductive, a second condenser for charging minus potential therein in accordance with conduction of said first transistor, a second transistor controlled by said minus potential of said second condenser, and a third transistor controlled by conduction of said second transistor, said third transistor regulating said engine rotation holding/arresting circuit.

10. An automatic control method for an engine of vehicles having an ignition switch for selectively connecting an electric source with an engine starter and an engine ignition circuit, an accelerator switch to be closed by depression of an accelerator pedal of the vehicle and a clutch switch to be closed by disengaging operation of clutch means of the vehicle comprising, an operation cycle with steps of connecting said electric source with said ignition circuit and with said starter to operate said engine; cutting off current supply to said starter in response to engine rotation; detecting driving movement of the vehicle; maintaining current supply to said ignition circuit while said driving movement of the vehicle is detected; blocking current supply to said ignition circuit to stop said engine rotation when the vehicle is arrested, and inhibiting the blocking of current supply to said ignition circuit for a predetermined time upon start of said engine to permit said vehicle to move.